PKEFACE. 



THE number of works which treat of microbes is 

 already considerable, but they have all been written 

 for a special public of physicians or naturalists, and 

 imply that the reader is familiar with the ideas 

 already established on pathology or on cryptogamic 

 botany. 



Although the science of microbes is of recent 

 origin, it has made immense progress in the course of 

 a few years. It is, moreover, essentially a French 

 science, since it is owing to Pasteur's admirable 

 labours, as well as to his solid genius, aided by the 

 faith and energy of his disciples, that this science 

 has been able to overcome the prejudices of ages, and 

 to penetrate into the very heart of the ancient theory 

 of medicine, so as to transform and regenerate it. 



Every one now speaks of microbes, yet few of those 

 who make use of the term have any clear conception 



